Potentially not THAT bad
If they're running in isolation, locked down, maybe just for compatibility with an old application then that seems pretty reasonable.
I had to repair a system running Windows 98 a few months ago. An embedded system that's been running every day for 20 years (rebooted daily, mind- it's still Win98) and shows no sign of failing, except for the date/time backup battery being too old to work (it was a soldered-on model, it's been out of service for about 10 years but they decided to renew it). I've no significant worries about that system outlasting the rest of the system it's a part of.
Why upgrade if it's not broken and there's no benefit?
Biting the hand that feeds IT
